SGER: Biomechanical Modeling to Forensic Estimation of Time Since Death

生物力学建模，以法医估计的时间，因为死亡摘要这一建议旨在解决的问题：“可以为人类的死亡时间估计从测量的变化，在特定的组织死后的机械材料性能？“一个由法医人类学家、解剖学家和机械工程师组成的多学科小组已经成立，试图回答这个问题。 由于这项研究处于初步阶段，国家科学基金会的“探索性研究小额赠款”是为该项目提供初始资金的适当机制。为了深入了解死后人体组织的机械降解，必须从身体中以相对较慢的速度分解的位置选择组织。 由于组织包裹，我们选择脊柱中的椎间盘（纤维环）作为本研究最可能的试验样本，但是，在制定试验方案时，将考虑其他组织（例如牙齿）。 最初，将从死亡时间已知的新鲜（未保存）尸体中采集三个（受成本限制）人体脊柱。 在规定的时间间隔内，通过手术从脊柱的胸椎和腰椎区域取出椎间盘。 将对这些收获的椎间盘进行宏观和微观描述，然后通过Instron 8511机械试验机施加的准静态、动态和时间依赖性压缩试验确定材料的机械性能。 此外，还将对使用超声技术的试点研究进行调查。将使用幂律、指数律、单应性或适用于生物材料的其他适用本构律对从力学试验中获得的载荷和变形数据进行建模，以确定死亡后特定时间的材料参数。 预计将出现材料参数与死亡时间之间的趋势。

Biomechanical Modeling to Forensic Estimation of Time Since DeathAbstract This proposal is designed to address the question: "Can the time of death for a human be estimated from measured changes in mechanical material properties of specific tissues post-mortem?" A multidisciplinary team, consisting of a Forensic Anthropologist, an Anatomist and a Mechanical Engineer, has been formed to attempt to answer this question. Since this research is at such a preliminary stage the NSF "Small Grants for Exploratory Research" is the appropriate mechanism for initial funding of the project. To gain insight into the mechanical degradation of human tissue after death, the tissue must be chosen from a location in the body which decomposes at a relatively slow rate. Because of tissue encapsulation, we have chosen intervertebral discs (annulus fibrosus) in the spine as the most likely test specimens for this study, however, other tissues (e.g. teeth) will be considered as the testing protocol is developed. Initially, three (limited by cost) human vertebral columns will be harvested from fresh (unpreserved) cadavers for which time of death is known. The intervertebral discs will be surgically extracted from the thoracic and lumbar regions of the spinal columns at specified time intervals. These harvested discs will be described macroscopically and microscopically, then mechanical material properties will be determined from quasi-static, dynamic and time-dependent compression testing imposed by an Instron 8511 Mechanical Testing Machine. Additionally, pilot studies using ultrasound techniques will be investigated. The load and deformation data acquired from the mechanical tests will be modeled using the power law, exponential law, homography or other applicable constitutive laws appropriate for biological material to determine material parameters at specific times since death. It is expected that a trend between the material parameters and time since death will emerge.